Tourniquet

Abstract

A pneumatic tourniquet has a constricting device that comprises a rocker, such that when the rocker is angularly displaced by contact with a wounded limb, a clamping force is applied by a rocker surface and a clamping edge onto a sealing element to prevent flow of the pressurized gas from an interposed inflated strap to a free end, causing the strap free end to be considerably thinner than the main strap section. In one embodiment, a gas flow control assembly comprises a casing containing a force transmitting element and a gas cartridge; and a pivotable activation handle, wherein, upon pivoted displacement of the activation handle, pressurized gas is caused to be discharged from the gas cartridge and flow to an interior of the strap. In other embodiments, the pneumatic tourniquet comprises one or more of a flow control unit, a manual pressure release initiator, and a puncture mitigating connection section.

The invention claimed is: 
     
       1. A pneumatic tourniquet, comprising:
 a) an inflatable strap adapted to receive pressurized gas and to be wrapped around a wounded limb to provide a desired hemorrhage suppressing force; 
 b) a flexible sealing element; and 
 c) a constricting device cooperating with a free end of said strap in such a way that said free end is unrestrainably displaceable within said constricting device until being clamped thereby when said strap is sufficiently tensioned to transmit the hemorrhage suppressing force, 
 wherein said constricting device comprises a housing member and a rocker rotatably mounted onto, and within, said housing member by a longitudinally extending axle, said rocker being configured to be angularly displaced about said axle until a surface of said rocker is set in clamping relation with a clamping edge of said housing member while said strap is interposed between said rocker surface and said clamping edge, in response to a force applied by the wounded limb onto said rocker when said strap is sufficiently tensioned, 
 wherein a clamping force applied by said rocker surface and said clamping edge onto said sealing element prevents flow of the pressurized gas from a circumferential pressure applying section of said strap which is wrapped around the wounded limb to said free end, causing said strap free end to be considerably thinner than said circumferential pressure applying section; 
 d) a casing which contains a puncture unit housing with which a gas cartridge filled with pressurized gas is coupled, a puncture pin that terminates with a pointed end, and an outlet port; and 
 e) means external to the casing for drivingly contacting said puncture pin by an amplified activation force to an inwardly displaced position at which the pointed end of said puncture pin punctures a puncturable cover normally sealing said gas cartridge, causing the pressurized gas to be discharged from the gas cartridge and flow via said outlet port to an interior of the inflatable strap. 
 
     
     
       2. The pneumatic tourniquet according to  claim 1 , wherein the strap is configured with first and second sections of different widths, wherein said second section is a circumferential pressure applying section which is narrower and longer than said first section and is adapted to be wrapped around the wounded limb in order to apply circumferential pressure and to suppress hemorrhaging, and said first section is wrappable around at least most of the wounded limb to facilitate substantially even distribution of pressure applied to a surface of the wounded limb and transmission of the desired hemorrhage suppressing force to the wounded limb via said second section. 
     
     
       3. The pneumatic tourniquet according to  claim 2 , wherein the first and second sections are made of different materials each of which having a different degree of flexibility, such that the second section becomes narrower and longer than the first section following inflation of the strap with the pressurized gas. 
     
     
       4. The tourniquet according to  claim 2 , wherein the strap is configured with a plurality of serially interconnected cells and with a neck portion that extends between two adjacent cells, to facilitate flow of the pressurized gas between one cell to another. 
     
     
       5. The pneumatic tourniquet according to  claim 1 , further comprising a member to which the strap is securable, and one or more elements movably connected to the strap-securable member and to the constricting device by which the constricting device is reorientable relative to the strap-securable member even when the strap is removed from the strap-securable member. 
     
     
       6. The pneumatic tourniquet according to  claim 5 , wherein the strap-securable member is a casing with which a gas cartridge filled with pressurized gas is coupleable therewithin and which is configured with an outlet port, a longitudinally displaceable force transmitting element, and means external to the casing for drivingly contacting said force transmitting element by an amplified activation force to forcefully contact and open at least a portion of an occluding element normally sealing said gas cartridge, causing the pressurized gas to be discharged from said gas cartridge and flow via said outlet port to a strap interior to provide the desired hemorrhage suppressing force. 
     
     
       7. The pneumatic tourniquet according to  claim 6 , wherein the force transmitting element is a puncture pin that terminates with a pointed end, or is an activation piston configured to cooperate with a valve stem associated with the gas cartridge. 
     
     
       8. The pneumatic tourniquet according to  claim 1 , wherein the sealing element is external to the strap. 
     
     
       9. The pneumatic tourniquet according to  claim 1 , wherein the external means comprises:
 a) a pivotable activation handle configured with a wide-area, substantially planar user-manipulatable surface having a width greater than 60% of the width of the casing; 
 b) a laterally extending beam which is rotatably mounted in corresponding seats provided with said casing to define an axis of rotation of said activation handle; and 
 c) a cam which is fixedly connected to the beam and is in drivable proximity with said puncture pin,
 wherein a ratio of a longitudinal length of said user-manipulatable surface, extending to a line coinciding with the beam and the axis of rotation, to the longitudinal length of the cam from the axis of rotation ranges from 16-22:1, 
 wherein, upon pivoted displacement of said activation handle about its axis of rotation, an amplified activation force provided by said ratio is transmitted by said cam that drivingly contacts said puncture pin to forcefully contact and open at least a portion of said puncturable cover causing the pressurized gas to be discharged from said gas cartridge and flow via said outlet port to the interior of the inflatable strap. 
 
 
     
     
       10. The pneumatic tourniquet according to  claim 6 , wherein the external means comprises:
 a) a pivotable activation handle configured with a wide-area, substantially planar user-manipulatable surface having a width greater than 60% of the width of the casing; 
 b) a laterally extending beam which is rotatably mounted in corresponding seats provided with said casing to define an axis of rotation of said activation handle; and 
 c) a cam which is fixedly connected to the beam and is in drivable proximity with said puncture pin,
 wherein a ratio of a longitudinal length of said user-manipulatable surface, extending to a line coinciding with the beam and the axis of rotation, to the longitudinal length of the cam from the axis of rotation ranges from 16-22:1, 
 
 wherein, upon pivoted displacement of said activation handle about its axis of rotation, an amplified activation force provided by said ratio is transmitted by said cam that drivingly contacts said force transmitting element to forcefully contact and open at least a portion of said occluding element causing the pressurized gas to be discharged from said gas cartridge and flow via said outlet port to an interior of the inflatable strap. 
 
     
     
       11. The pneumatic tourniquet according to  claim 10 , wherein the occluding element is a puncturable cover and the force transmitting element is a puncture pin that terminates with a pointed end that is drivable to an inwardly displaced position at which the pointed end punctures the puncturable cover. 
     
     
       12. The pneumatic tourniquet according to  claim 10 , wherein the force transmitting element is an activation piston configured to cooperate with a valve stem associated with the gas cartridge. 
     
     
       13. The pneumatic tourniquet according to  claim 1 , further comprising:
 a) a housing member, which is configured with an internal cavity; 
 b) a shell connected to the housing member and formed with a plurality of parallel passageways; and 
 c) a pressure regulating unit configured with an inlet that passes through the housing member for receiving pressurized gas upon demand; and 
 d) a piston axially and differentially displaceable within the internal cavity to define at a distal end thereof a supply chamber in fluid communication with atmospheric air and, at a proximal end thereof, a regulating chamber adjoining said shell, said regulating chamber being in fluid communication with said inlet by a tube passing through an entire thickness of said piston and with the interior of the strap via one of said passageways. 
 
     
     
       14. The pneumatic tourniquet according to  claim 13 , further comprising:
 a) the housing member, which is configured with the inlet for receiving pressurized gas upon demand; 
 b) the tube, which is hollow so as to be in fluid communication with the inlet and has an outer diameter of less than 2.5 mm and a distal end with an unsmooth finish; 
 c) the piston which is intermediately bored and connected to, and which has an outer diameter significantly greater than, the tube; and 
 d) a fixed sealing element,
 wherein, following flow of the pressurized gas into said regulating chamber through the tube, the piston is caused to be distally displaced by a pressure differential between the pressure in said regulating chamber and in said supply chamber until the distal end of the tube is occluded by said sealing element, to prevent additional inflow of the pressurized gas. 
 
 
     
     
       15. The pneumatic tourniquet according to  claim 13 , further comprising a manual pressure release initiator axially displaceable within another one of said passageways that is in fluid communication with said regulating chamber and with atmospheric air, which, when distally displaced to a fullest extent, contacts said piston to occlude said tube and to prevent additional inflow of the pressurized gas to said regulating chamber, and also provides a clearance relative to a wall of said another passageway to cause egress of the pressurized gas received in said regulating chamber to the atmospheric air and to selectively reduce the pressure of the fluid within said strap interior. 
     
     
       16. The pneumatic tourniquet according to  claim 1 , wherein the puncture pin has, for at least one region thereof, a solid shaft of a uniform diameter that is cut at an angle to define a planar surface having a sharp peripheral edge configured such that the pointed end is coincident with the peripheral edge and with an outer surface of the shaft, producing an unsealed passageway adjoining the shaft outer surface along which the pressurized gas is discharged from the gas cartridge following puncturing of the cover by the pointed end.